To gain insight regarding the mechanisms that extend heteroduplex joints in Escherichia coli recombination, we investigated the effect of recG and ruv genotypes on heteroduplex strand polarity in intramolecular recombination products. We also examined the cumulative effect of mutational inactivation of RecG and single-strand-specific exonucleases on recombination proficiency and the role of Chi...

We have found that most spontaneous mutations in the thyA gene of Escherichia coli selected for resistance to trimethoprim result from a TA to AT transversion at a single site within an imperfect inverted repeat or quasipalindrome sequence. This natural quasipalindrome within the coding region of thyA contains an extraordinarily potent hotspot for mutation. Our analysis provides evidence that t...

The genes encoding the small nucleolar RNA (snoRNA) species snR190 and U14 are located close together in the genome of Saccharomyces cerevisiae. Here we report that these two snoRNAs are synthesized by processing of a larger common transcript. In strains mutant for two 5'-->3' exonucleases, Xrn1p and Rat1p, families of 5'-extended forms of snR190 and U14 accumulate; these have 5' extensions of ...

Novel 2'-O,4'-C-ethylene nucleosides have been synthesized as building blocks for antisense and antigene oligonucleotides. 2'-O,4'-C-Ethylene-bridged nucleic acids (ENA) comprising 2'-O,4'-C-ethylene nucleosides have considerable affinity to complementary RNA and double-stranded DNA. Incorporation of 2'-O,4'-C-ethylene nucleosides into oligonucleotides dramatically increase their resistance aga...

vi1An Introduction1.1DNA Replication11.1.2 Leading and Lagging Strands41.1.3 Interference61.2Secondary Structures91.2.2 Quasi-palindromes101.2.3 Quasi-palindrome Mutational Reporters12References17 2Materials and Methods2.1Growth Medium212.2Strain Construction212.3Mutational Rate Deter...

Lactobacillus acidophilus R-26, which requires preformed deoxyriboside for its growth, is able to grow in a basal medium supplemented with nitrophenyl esters of thymidine 3'- and 5'-phosphates. Mutants unable to grow on the thymidine phosphate esters were isolated and classified thus far into two classes. One class of mutants that are unable to grow on the diesters have modified exonucleases, t...

The degradation of small RNAs in plants and animals is associated with small RNA 3' truncation and 3' uridylation and thus relies on exonucleases and nucleotidyl transferases. ARGONAUTE (AGO) proteins associate with small RNAs in vivo and are essential for not only the activities but also the stability of small RNAs. AGO1 is the microRNA (miRNA) effector in Arabidopsis, and its closest homolog,...

DNA repair mechanisms are essential for preservation of genome integrity. However, it is not clear how DNA are selected and processed at broken ends by exonucleases during repair pathways. Here we show that the DnaQ-like exonuclease RNase T is critical for Escherichia coli resistance to various DNA-damaging agents and UV radiation. RNase T specifically trims the 3' end of structured DNA, includ...